This patch add paravirtualization hooks in the arch initializationprocess. paravirt_arch_setup() lets the guest issue any specificinitialization routine, and skip all the rest if it see fits, whichit signals by a proper return value.

In case the initialization continues, we hook at least memory_setup(),so it can handle it in its own way.

The hypervisor can make its own ebda mapping visible by providingits custom ebda_info function.